1. Field of the Invention
This invention relates generally to a magnetic tape cassette and, more particularly, is directed to improvements by which a magnetic tape contained in the cassette casing is protected when not in use.
2. Description of the Prior Art
Recording and reproducing apparatus has been recently proposed in which an analog signal, such as, an audio signal or the like, is converted to a digital signal, for example, a PCM (pulse code modulated) signal which is then recorded and/or reproduced. Such PCM recording and reproducing apparatus generally uses, as its record medium, a magnetic tape contained in a magnetic tape cassette. However, one disadvantage of PCM recording is that, if an oily deposit, for example, from a fingerprint or the like, or dust adheres to the magnetic tape, a dropout will result in the reproduced signal. In an attempt to avoid the foregoing problem, it has been proposed to provide a magnetic tape cassette with a casing having an opening through which access may be had to magnetic tape contained in the casing, and with a lid pivoted on the casing for movement between a closed position covering the opening for protecting the tape and an opened position in which the lid uncovers the opening of the casing for providing access to the tape therethrough, as by a recording/reproducing head. In magnetic tape cassettes of the kind being described, the casing has spaced, parallel top and bottom walls and a peripheral wall therebetween which is formed with the opening along a substantially straight side of the casing at the front of the latter, and the lid includes an elongated plate portion dimensioned to extend along the straight side of the casing and having ears projecting from its opposite ends and at which the lid is pivotally mounted on the casing. In the closed position of the lid, its elongated plate portion is closely adjacent to the peripheral wall along the straight side at the front of the casing so as to cover the opening and thereby shield the tape within the casing and, in the opened position of the lid, the latter is pivoted upwardly or downwardly so as to move the elongated plate portion away from in front of the peripheral wall at the straight side of the casing. However, in order to permit such pivotal movements of the lid, it is necessary to provide a substantial clearance between its elongated plate portion and the adjacent peripheral wall of the casing in the closed position of the lid with the result that the space required in a recording and/or reproducing apparatus for accommodating the magnetic tape cassette is undesirably increased. Furthermore, in the existing magnetic tape cassette, the lid may be inadvertently pivoted from its closed position toward its opened position when the cassette is not in use.